1. Field of the Invention
The present invention relates to a method and apparatus for cleaning objects, and particularly to a portable and continuous washing system.
2. Background of the Invention
Maintaining large objects, such as wheelchairs, shopping carts, and bakery racks in a clean and sanitary condition can be problematic. Wheelchairs, in particular, are commonly stained with urine, milk scale and large food particles. Many institutions still wash wheelchairs by hand in a conventional shower stall, using bottled spray cleaner and a rag or sponge. Such a process can be extremely unpleasant for the worker and typically takes up to 30 minutes or more per wheelchair.
Some institutions use a type of "power washer" to clean large objects using pressures of up to about 1500 psi. When water is dispensed at such high pressures, however, the wheel bearings and other components of the object can be negatively impacted. Furthermore, this task is typically completed in an unsanitary parking lot.
An improved method for cleaning wheelchairs currently used by a few institutions involves the use of a wheelchair cleaning machine resembling a large dishwasher. However, these machines are capable of washing only one wheelchair at a time and are labor-intensive to operate and maintain. Such an apparatus is described in U.S. Pat. No. 5,133,375 to Schinzing et al and in U.S. Pat. No. 5,285,802 to Soderquist.
A method for washing objects is described in U.S. Pat. No. 5,622,196 to Luongo. In Luongo, objects enter from one end and exit from another after being cleaned with moving sprayer arms at very high pressures of about 3000 psi. Since the water in Luongo is not heated and there is apparently no rust inhibitor used nor any drying means for the exiting objects, it is likely this process promotes rusting of metal objects. Furthermore, the use of such high pressures likely negatively impacts not only wheel bearings, but surface coatings as well.
A trailer-mounted cleaner for cleaning grocery carts is described in U.S. Pat. No. 3,179,117 to Gibson, et al. A group of "nestled" carts in Gibson are loaded through the side opening of a trailer through use of trams, and are "jostled" through the washing chamber to exit at the opposite end. Specifically, the sanitized carts exit the trailer at a point when the lugs of a tram chain come out of engagement with the bottom of the carts, such that the group of carts slides out the exit by force of gravity. There is no drying means provided for in Gibson as the carts are allowed to air dry on site or in the store. The jostling encountered by the carts in Gibson likely negatively impact bearings on the shopping carts, which can shorten their useful life considerably. It is also likely that since the carts remain nestled throughout the cleaning process, each cart is not as thoroughly cleaned as it would be if cleaned individually. Furthermore, the location and manner of the exiting means are very impractical as this arrangement requires an operator to be present when the carts begin sliding down the exit ramp, so they can be stopped before they roll away from the apparatus.
Thus, what is needed is a low-cost and practical method for thoroughly cleaning wheelchairs, shopping carts, bakery racks and other large objects at a high rate of speed using minimal labor, without causing damage to the objects themselves.